heres what i did and it can turn off and works with ping pong cut it directly in half so its even then put the LED throwie in it (i put 2 for a cool effect) then just tape on the seam then to turn off take off the tape :)

This thing work better than I thought it would. The only problem is YOU CANT TURN IT OFF!!! 7/10

any place that i can get a big bag of super cheap ping pong balls ?

probly ebay, i got 72 of the ones i used in this instructables on ebay for 15 bucks. They are not real ping pong balls made of cellulose, so u cant make smoke bombs, but they are plastic ones that work well for projects.

of course -- but are they good for actually playing ping pong?
(not your instructable, but the original ball...)
although it would be cool to be able to play in the dark...

theyre al right doesnt beat original tho

If you don't want to cut the ball in half, you could just drill a hole or cut a slice into the ball and put the LED in that way. Then you only need a little bit of glue to cover the hole and its removable so you can shut it off or change the batteries.
I'm thinking this would make a great cat toy.
Here's a tip. Make two of these. Put a string through each one so you have a ball on a string in each hand. Turn off the lights and spin them around in the dark. You get a cool streaky effect.
But be careful.
I did that once with a glow in the dark cat toy. I sneaked up on my wife. It scared her so bad she nearly beat me half to death with a couch pillow. We had only been married a week so she wasn't used to my sick sense of humor. LOL
This is great fun. Thanks for posting it.

if u just make a peircing in the 'seam' of the ball you can pull the ball apart along the seam and you get a very neat cut straight along the middle.
put the LED inside and glue it up witth hot glue!you can the cut off the excess hot glue to make it neater.

i didnt no that, thnks!

No problem

wat if u just cut 1 ball in half &put the LED IN, then super glued the ball back together

It is hard to glue the ping-pong ball together. Think of how thin the ball is.